Hydraulically actuated steering systems typically include a yoke or helm pump that actuates a steering cylinder used to change the position of a corresponding control surface, such as a rudder or actuated propulsion system on a ship or various control surfaces on an airplane. Conventional autopilot installations for hydraulic steering systems include a motorized autopilot pump and a reference transducer or sensor coupled to the steering cylinder and/or steering control surface to provide steering angle/position feedback to the autopilot controller.
Most conventional autopilots are enabled and disabled through manipulation of a keypad containing “auto” and “standby” buttons, where a user must manually disable the autopilot before being able to steer the corresponding vehicle without being fought by the autopilot. Other types of conventional autopilots require a user to overpower the autopilot before the autopilot disengages, but this technique is typically unavailable in hydraulic steering systems because the helm pump cannot easily overpower the autopilot pump when they are coupled in parallel, as is typical with hydraulic steering systems with integrated hydraulically actuated autopilots. Moreover, any substantial delay (e.g., to find and push a “standby” button and/or to spin a helm faster than an autopilot can pump against) risks collision with an object in the path of the mobile structure. Thus, there is a need for an improved methodology to provide expedient, accurate, and reliable release of an hydraulically actuated autopilot for a mobile structure.